Thermoelectric devices are used to harvest electrical energy from a thermal energy source as a function of heat flow through materials in the device sweeping charge carriers in the materials in the direction of the heat flow.
Prior thermoelectric device configurations typically include a first bar of a first material of a first charge carrier type, such as an n-type semiconductor, arranged between a hot surface and a cold surface, and a second bar of a second material of a second charge carrier type, such as a p-type semiconductor, also arranged between the hot surface and the cold surface, and electrically connected to the first bar at one end. As heat flows from the hot surface to the cold surface through the first bar, charge carriers in the first bar, such as electrons in an n-type semiconductor, are swept in the same direction. Similarly, as heat flows from the hot surface to the cold surface through the second bar, charge carriers in the second bar, such as holes in a p-type semiconductor, are also swept in that same direction. From an electrical perspective, a current flows from the hot surface to the cold surface through the first bar, through the electrical connection to the second bar, and from the cold surface to the hot surface through the second bar, resulting in a corresponding power generation. Prior devices may connect a plurality of these configurations in series to increase the power generated.
However, such configurations suffer from several problems. First, one of the two different types of materials may have better thermoelectric properties than the other, such as generating a greater current flow from the same amount of material in response to the same heat flow, potentially leading to inefficiencies in both power generation and device area utilization. Second, manufacturing different materials of different charge carrier types in the same device typically requires separate complex processing steps, and associated costs, for each material.
Therefore, a need exists for thermoelectric devices that provide one or more of improved power generation, device area utilization, manufacturing simplicity or cost.